Lathe center



March 15, 1949. VANDERWALL 2,464,359

LATHE.CENTER Filed April 5, 1946 E9. 4'. .Fig. .5?-

28 5*112 //8 28 Li I 20 INVENTOR. ERNEST H. VA NDERWALL ATTORN E VPatented Mar. 15, 1949 UNITED "STATES PATENT OFFICE Applicatio: s5.,292,1). 660,006

' 1 My invention relates to improvements in a lathe center.

One of the objects ofmy invention is to provide a lathe center having arotating spindle in which provision is made for compensating for theexpansion of the work piece due to heat generated in it as the cut i gtool is used.

Another object of my invention is to provide means for assuring the freerotation of the spindle under all conditions of endwise pressure.

Another object of my invention is to provide a novel means for allowingfor endwise movement of the rotating Spindle portion in the housing.

Another object of my invention is to provide a novel means for securingthe spindle in place and also for removing the spindle from its housingwhen it is desired to substitute a spindle having a female instead of amale end.

A preferred embodiment of m invention is shown in the drawings in which-Fig. 1 is a longitudinal cross-sectional view;

Fig. 2 is a cross-sectional view taken on the line 11-11 of Fig. 1 inthe direction of the arrows;

Fig. 3 is an end view taken from the right hand end of Fi l;

Fig. 4 is a cross-sectional view taken on the line Of 5; and

Fig. 5 is a plan view of a modified form of spindle insert.

It is not my intention to limit this invention to the details of thisdisclosure except as required by the appended claims because differentmanufacturers may prefer to make variations in the structure and yetcome within those claims.

The device includes an outer shell III which has its surface H tapered,usually to the Morse taper,

- to fit in the spindle in the headstock or in the tailstock of a lathe.This shell I II has a bore 12 usuallywith a straight cut which extendssubstantially to its bottom end where at l3 its end is rounded so as toreceive a ball H to provide a hard and yet relatively frictionlesssurface against which the spindle will be thrust.

In place of the ball i4, I may on certain types of installationssubstitute a thrust bearing usually of the ballbearingtype, using muchsmaller balls than the balls shown at I. In this case the end I! will beflat or have a shoulder to receive the thrust hearing.

The shell. at II has a recess and a counter-sink in which is threaded ascrew it the purpose of which is to hold the spindle l8 in the shell. Italso has other functions, namely, for oiling when the screw I 8 isremoved and also to permit an air-Jet nozzle to be applied to the recessIt so the 2 air will blow the spindle out of the shell. This latteravoids the necessity of having a hole in the back end of the shell andenables the easy removal of the spindle where it is desired to insertanother spindle in its place.

Itis not absolutely necessary but I have found it advisable to have athrust washer l1 bearing against the thrust ball it where that type ofball used.

The spindle I8 is made to form a snug rotating fit with the bore l2 ofthe shell. It also has an annular groove l9 which is axially wider thanthe diameter of the screw l6 so as to allow a reasonable axial. movementof the spindle II with relation to the shell i0. The reason for this is.

to allow for the expansion of the work being sup-' ported by the pointof the spindle and to allow the spindle l8 to move axially to the leftas the work (to the right of the point 20) expands and exerts additionalpressure on the spindle IS.

The compensation for this axial movement of the spindle l8 to the leftis provided for in the two reverse cuts 2i and 22 near the end 23 of thespindle l8. The nature of these reverse cuts is shown more clearly inFig. 2 which is a cross-sectional view taken on the line 11-11 ofFig. 1. The shaded portion 24 at the top is the portion which connectsthe end 25 of the splndie l8 with the main body portion of the spindle.The portion lying below the dotted line 28 in Fig. 2 and marked 21 issimilarly shown on the spindle l8 in Fig. 1. By means of these cuts madefrom opposite sides of the spindle l8 the end portion 25 is moveableaxially with respect to the main portion of the spindle I 8 and providesa spring or resilient cushion eflect so that the distance from the point20 to the end 25 can be reduced as the work supported on the spindleexpands due to heat or other reasons. Stated differently, the cut orcuts partway across the spindle I 8 provide a portion of the spindlestock which is unsupported with relation to the its axially adjacentarea.

While I have shown in Fig. 2 and Fig. 1 two of these cuts 2| and 22,made from opposite sides of the spindle I 8, it is possible to haveseveral of these cuts or to have them come in from diflerent angles. Forexample in Figs. 4 and 5 I have shown a spindle l8 having three cutsfrom opposite sides of the spindle nearest the face 25. For example, thecut at 28 on Fig. 4 is the cut at 28 on Fig. 5. The solid portion 29 onFig. 4: is the solid portion 29 on Fig. 5 and the solid g iortison 30 onFig. 4 is the solid portion 30 on 3 While I have referred to this deviceas used in a. lathe, it also has use in drill presses or other machineswhere a center is needed.

What I claim is: l. A compensating center including an outer shellhaving a bore extending axially thereima single spherical thrust bearingseated against a' closure in said bore, a wear plate engaging saidbearing, a spindle fitted in said bore in rotative relation thereto sothat said bore serves as a bearing for substantially the full length ofsaid spindle, an annular groove formed intermediate the ends of saidspindle, a pin threaded through said shell and extending into saidgroove, said groove having a greater axial dimension than said pin, anda plurality of radially extending cuts crossing the axis of said spindleto provide a resilient means between said plate and the outer end ofsaid spindle as the same supports a workpiece.

2. A compensating center including an outer shell having a boreextending axially therein,

means forming a thrust bearing seated against a closure in said bore, aspindle fitted in said bore in rotative relation thereto so that saidbore serves as a bearing for substantially the full length of saidspindle, means to rotatively retain said spindle in said bore. andaplurality of radially extending cuts crossing the axis of said spindleto provide a resilient means between said bearing means and the outerend or said spindle as the same supports a workpiece.

ERNEST H. VANDERWAIL.

REFERENCES CITED The following references are of record in the v

